Automatic clamp apparatus for IV infusion sets used in pump devices

ABSTRACT

A clamp apparatus for selectively occluding a resilient tube to prevent free flow of fluid in the tube. The device comprises a base member to which the resilient IV tube is attached or through which it passes, and a slide clamp that slides relative to the base member and relative to the tube. The aperture in the slide clamp has a relatively open hole at one end, through which the tube passes when the slide clamp is an open position, allowing fluid to flow through the tube. The aperture also has a relatively constricted slot at the other end, through which the tube passes when the slide clamp is in the occluding position, preventing fluid flow through the tube. A deflectable cantilevered locking arm on the base interlocks with a detent on the slide clamp to lock the slide clamp at the occluding position to avoid inadvertent free flow. A release tab that is used to release the locking arm from the slide clamp is located off center to avoid inadvertent activation. The deflectable arm is unstressed when the slide clamp is in either the occluding or the open positions. A stop device prevents over-stressing the release tab when it is moved. In one embodiment, the clamp apparatus may be slid along the IV tube to a desired location.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/892,941, filed Jul. 16, 2004, now U.S. Pat. No. 7,124,996. U.S.application Ser. No. 10/892,941 is incorporated herein by reference.

FIELD OF INVENTION

The invention is generally related to clamps used on flexible IV tubingin the field of intravenous (IV) infusion devices such as peristalticpumps, and more particularly, to clamping devices used to prevent thefree flow of fluids through an IV tube when the infusion pump isdisengaged from the IV tube.

BACKGROUND OF THE INVENTION

It is a common practice to deliver fluids such as medications to apatient intravenously by means of a pumping device, such as aperistaltic pump. Such pumps are useful because they can deliver themedication in a highly controlled and precise fashion, and because theydo so without coming in contact with the medication. The fluid is movedthrough a flexible IV tube by pressing a pumping member against the tubesufficiently to move the fluid in the tube downstream towards thepatient. In the case of peristaltic mechanisms having multiple pumpingfingers, the fingers are moved against the tube in a sequential mannerfrom upstream to downstream to sequentially occlude the tube therebymoving the fluid in the tube downstream towards the patient. When the IVtube is mounted correctly in the pump, the IV tube is at all timesoccluded by one of the pumping members, thereby preventing the “freeflow” of fluid to the patient. “Free flow” of medical fluids isundesirable since the flow of the fluid is uncontrolled and theprescribed treatment is not followed.

It is common for the peristaltic pumping mechanism to be located in ahousing with a hinged door. The tube through which the fluid is to bemoved is placed in contact with the pumping mechanism inside the door,with the ends of the tubing typically extending out the top and bottomof the door opening. As the door is shut over the tube, a platen on theinside of the door presses against the IV tube to provide a backingsurface against which the pumping members can occlude the tube. Theplaten is typically spring loaded, although not always, against thepumping mechanism so that one or more of the pumping fingers of thepumping mechanism occludes the tube once the door is shut over the tube.This then prevents free flow while the door is shut.

This arrangement of the IV tube relative to the pumping mechanismrequires that there be some means for preventing flow in the tube whenthe door of the pump is open. Merely opening the pump door would relievethe tube from the occluding pumping mechanism/platen combination andfree flow could possibly occur. This could result in the uncontrolledinfusion of medication into the patient under the influence of thestatic head pressure in the tube, or blood from the patient could flowback into the IV tube. Known devices for preventing the unwanted flow inthe tube include manual clamps on the tube separate from the infusionpump, and automatic occluding devices mounted on the pump. The manualdevices require some manipulation skill on the part of the attendingtechnician, and there is always the chance that the technician willforget to properly time the manual clamping process of the tube beforethe door of the pump is opened. Furthermore, the door may beaccidentally opened, resulting in free flow in the tube.

Automatic devices mounted on the infusion pump for assisting in clampingand unclamping infusion tubes have improved. In particular, thereliability in timing the occlusion and release (unocclusion) of thetube with the disengagement and engagement, respectively, of tube withthe pumping members has improved. Typically, the action of opening thedoor is relied upon to initiate the occlusion of the IV tube by a clamp,and the action of closing the door is relied upon to initiate therelease or unocclusion of the tube by an IV tube clamp. However, therestill can occur the possibility of an inadvertent free flow of fluidthrough the IV tube due to operator error in regard to use of suchdevices.

Hence, those skilled in the art have identified a continuing need toprovide an improved apparatus that will automatically and positivelyocclude an IV tube before the occluding pumping mechanism is disengagedfrom the tube. A further need has been recognized for an apparatus thatwill automatically and positively maintain the IV tube in an occludedstate until after the occluding pumping mechanism is engaged with thetube. A still further need has been recognized for an apparatus thatwill reliably occlude the IV tube, that is inexpensive to manufacture,and is easy to use. Yet a further need has been recognized for anapparatus that can be manually operated between occluding andnonoccluding configurations. The present invention fulfills these needsand others.

SUMMARY OF THE INVENTION

Briefly and in general terms, the present invention is directed to aclamp apparatus for selectively preventing fluid flow through aresilient tube and comprises a base having a tube aperture at which theresilient tube may be located, the base having a longitudinal centerline, a slide clamp slidably mountable on the base for movement betweenan occluding position and an open position, the slide clamp having alongitudinal center line, a clamp aperture formed in the slide clamp forreceiving the tube therethrough, a constricted region formed in theclamp aperture, the constricted region occluding the tube to preventfluid flow through the tube when the slide clamp is in the occludingposition, an open region formed in the clamp aperture, the open regionallowing fluid flow through the tube when the slide clamp is in the openposition, a locking component formed on the slide clamp, and a flexiblecantilevered locking arm mounted on the base, the locking arm having arelease tab formed thereon but located at a position offset from thelongitudinal center line of the base, the locking arm being biasedtoward a locking position wherein the locking arm engages the lockingcomponent of the slide clamp to prevent movement of the slide clamp fromthe occluding position to the open position, and the release tab beingmovable to deflect the locking arm wherein the locking arm is disengagedfrom the locking component to allow subsequent movement of the slideclamp from the occluding position to the open position.

In accordance with another aspect of the invention, the tube aperture ofthe base slidably receives the resilient tube such that the base may beslid along the tube to a selected position when the slide clamp is inthe open position.

In other aspects of the invention, the locking arm further comprises arelease tab for releasing the flexible arm from the slide clamp, toallow subsequent movement of the slide clamp from the occluding positionto the open position. Further, the base comprises a stop surface locatedat a position adjacent the release tab to interfere with movement of therelease tab beyond a preselected range of movement. The slide clampcomprises a detent into which the locking arm is biased and located whenthe slide clamp is in the occluding position, the detent being largeenough to receive the locking arm without contact while the slide clampis in the occluding position whereby the locking arm is under no stress.The slide clamp further comprises a ramp to receive the locking arm whenthe slide clamp is in the open position, the ramp formed to be deeperthan the arm whereby the arm is not under stress when the slide clamp isin the flow position. The ramp is formed to guide the locking arm into adetent formed in the slide clamp as the slide clamp is being moved fromthe open position to the occluding position to thereby lock the slideclamp in the occluding position.

In yet other aspects, the aperture of the slide clamp is approximatelytear-drop shaped, the constricted region comprises an elongated slotportion, the flow region comprises a rounded portion, the tube islocated in the slot portion when the slide clamp is in the occludingposition, and the tube is located in the round portion when the slideclamp is in the open position.

In additional detailed features, the tube aperture comprises a tubesleeve within which a resilient tube end may be permanently mounted. Thetube aperture comprises a fluid passageway through the base, whereby theresilient tube is connected in fluid communication with the passageway.Further, the clamp apparatus comprises a pressure interface devicelocated in line with the resilient tube, the pressure interface devicehaving a pressure membrane mounted in a housing, the pressure membraneformed to conduct pressure increases and decreases of the resilienttubing to a pressure sensor located in a medical instrument.

In further aspects in accordance with the invention, the slide clampfurther comprises a front pushing flange large enough to receive a digitof an operator used to push the clamp apparatus into position in amedical infusion pump, the pushing surface being concave. The releasetab of the locking arm is located at a position other than behind thepushing flange. In a much more detailed aspect, the release tab islocated at a sideways position in relation to the pushing flange.Additionally, the base comprises a rounded mounting end whereby pressingthe clamp into operative position in an infusion pump is facilitated.

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the automatic clamp apparatus inaccordance with aspects of the present invention showing the slide clampin the occlusion position at which it is partially withdrawn from thebase;

FIG. 2 is a front left-side perspective view of the slide clamp shown inFIG. 1 showing the aperture, the detent, the ramp, and the pushingflange;

FIG. 3 is a bottom right-side perspective view of the slide clamp shownin FIG. 1 showing the aperture, the pushing flange, and the pullingprojections;

FIG. 4 is a top plan view of the slide clamp of FIGS. 1 through 3;

FIG. 5 is a left side, partially cutaway view of the slide clamp ofFIGS. 1 through 4 showing a pulling projection, the detent, and theramp;

FIG. 6 is a top, left side perspective view of the base showing alocking arm, a release tab, and a tube aperture;

FIG. 7 is a bottom, right side perspective view of the base showing thelocking arm and release tab;

FIG. 8 is a right side plan view of the base showing the release tab;

FIG. 9 is a cross-section left side view of the base showing the lockingarm and release tab;

FIG. 10 is a left side view of the base showing the tube aperture, therelease tab, and a portion of the locking arm, also shown in the angleof the locking arm with the upper base surface;

FIG. 11 is a bottom view of the base;

FIG. 12 is a top, left side perspective view of the automatic clampapparatus of FIG. 1 in which the slide clamp has been inserted fullyinto the base resulting in the flow configuration;

FIG. 13 is an operational view in which the tube is occluded by theaperture of the slide clamp, but a release boss and a pushing boss areabout to move the slide clamp to the open or flow position;

FIG. 14 is an operational view in which the tube is unoccluded for flowand a pulling hook is about to pull the slide clamp to the occludingposition; and

FIG. 15 is a view of the clamp apparatus having a pressure interfacedevice located as part of the tube upstream from the clamp forcommunicating the line pressure to a pressure sensor.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings with more particularity, in which likereference numerals refer to like or corresponding elements among theseveral views, FIG. 1 presents an automatic clamp apparatus 20 forintravenous (herein referred to as “IV”) infusion sets used in pumpdevices. The clamp apparatus 20 comprises generally a relatively open,box shaped base or frame 22 and a mating slide clamp 24. Both parts canbe formed by injection molding from various plastic materials. The solidbody of the slide clamp 24 is shaped and sized to slide within the base22. In the embodiment shown, the base 22 has a tower 26 formed on thetop surface 28 of the base, with the tower extending upwardly from thebase and substantially perpendicular to the base. The top end 30 of thetower 26 is formed as a female tube connector into which a resilient IVtube can be attached. A pumping tube or other type of fluid conduit canbe attached to the base by other means if desired. The open bottom end32 of the tower is attached to the base and it is also formed as afemale tube connector into which an IV tube or other conduit can beattached. The IV tube and the pumping tube can be the same tube ifdesired, simply threading the IV tube through the tower, through thebase, and through the slide clamp such that the automatic clampapparatus 20 can be slid along the IV tube to a desired location.

Referring now also to FIG. 2, the slide clamp 24 is penetrated from itstop surface 34 to its bottom surface 36 by an elongated aperture 38. Theelongated dimension of the aperture 38 is arranged on the slide clamp tobe parallel to the direction of the relative sliding movement betweenthe base 22 and the slide clamp 24. The aperture 38 of the slide clampcomprises an open portion 40 and an occluding portion 42. The openportion is large enough so that a tube received by the open portionwould not be occluded whereas the occluding portion is small enough sothat it would occlude a received tube. The width of the slot of theoccluding portion is sufficiently small that a selected IV tube passingthrough the slot would be completely occluded and would remain occludedagainst a foreseeable range of fluid pressures in the IV tube. The rangeof pressure against which the tube would remain occluded would includeat least the static head anticipated during normal use of the infusionapparatus.

The slide clamp 24 also includes a pushing flange 44 at its front edge46. The pushing flange is somewhat concave, although the “concave”surface may not necessarily be curved; it may in fact have convergingstraight surfaces or surfaces of other shapes. The purpose of thepushing flange is to guide the digit of an operator to the approximatecenter of the slide clamp for the purpose of mounting the entireautomatic clamp apparatus 20 (FIG. 1) into an infusion pump. Such anoperation may be seen by reference to U.S. Pat. No. 6,629,955 to Morris,particularly FIG. 10. U.S. Pat. No. 6,629,955 to Morris is incorporatedherein by reference. Guiding the digit of an operator to the center ofthe pushing flange is more likely to result in the application ofcenterline force on the automatic clamp apparatus and thereby to resultin the correct mounting of the clamp apparatus in the pump. Forconvenience, the shape of the pushing surface of the pushing flange 44is referred to as “concave” although the surfaces may be other thancurved, as discussed above. It will be noted that in this embodiment,the aperture 38 is also located on the longitudinal centerline 47 of theslide clamp.

Also shown in FIG. 2 is a locking detent 48 having a locking detent edge50. The particular operation of the detent will be shown later but itspurpose is to prevent movement of the slide clamp from the occludingposition to the open position in the base without intended action.Further shown is a ramp 52 at the front of the slide clamp for receivinga locking arm of the base when the slide clamp is in the open position.

Referring now to the perspective view of FIG. 3 and the views of FIGS. 4and 5, the bottom surface 36 of the slide clamp 24 includes pullingprojections 30 that project downwardly from the bottom surfacepresenting a substantially vertical pulling face 56 to engage the latchon the door of the pump housing (not shown) to withdraw the slide clamp24 partially out of engagement with the base 22 before the door isopened. Pulling or withdrawing the slide clamp partially out of the basemoves the slide clamp from its open position to its occluding position(FIG. 1). The pushing flange 44 of the slide clamp also presents asubstantially vertical pushing face against which the door of the pumpor some other device pushes to fully insert the slide clamp into thebase when the door of the pump is closing or after it has been closed.Pushing the slide clamp into full insertion with the base moves theslide clamp from its occluding position to its open position. Also shownin FIGS. 4 and 5 are the detent 48 and the ramp 52. Both are formed inthe material of the slide clamp and the depth of both can be best seenfrom FIG. 5.

Turning now to the base, there is shown in FIG. 6 the base 22 with aflexible cantilevered locking arm 60 that is molded into the top surface28 of the base, with its distal free end 62 biased downwardly below thetop surface 28 of the base. Biasing of the free end downwardly isaccomplished by molding the locking arm in a downwardly slopedconfiguration, but the biasing could also be accomplished by the use ofsprings or other means. A release tab 64 is formed on the locking arm60, projecting upwardly from the locking arm in the general direction ofthe tower 26. It will be noted that the release tab 64 is located at aposition sideways to the tower 26. The release tab is also offset fromthe longitudinal centerline 66 of the base. The free end 62 of thelocking arm 60 can be flexed upwardly by pressing the release tab 64 ina direction parallel to the centerline 66. Without departing from thespirit of the invention, multiple locking arms and tabs offset from thecenterline of the base may be used in place of the ones shown.

It should also be noted that the depth of the detent 48 and the size andangle of the locking arm 60 are carefully selected so that when thelocking arm is located in the detent, it is unstressed. That is, it doesnot touch the bottom of the detent with any significant force. This isimportant in that if the locking arm is formed of plastic material orother material that exhibits “creep,” it may change shape if it isexposed to constant stress for an extended period. For example, if theclamp apparatus were stored in the occluding position (FIG. 1) for anextended period where the locking arm was in contact with the bottom ofa shallower detent and was under continual stress due to constantcontact with the detent, the locking arm may creep to where that storageposition is the new at rest position of the locking arm. The locking armwould then become less effective. Thus, forming the detent and lockingarm as described above so that the arm is unstressed will result in aclamp apparatus that is unaffected by storage. Similarly, the ramp isalso of a depth that leaves the locking arm unstressed when at thelowest point of the ramp, as is the case in the open position shown inFIG. 12.

The base also includes its side edges 68 formed into rails 70 that lieparallel to the direction of the relative sliding movement of the slideclamp in the base (FIG. 1). When the slide clamp 24 is slidingly engagedwith the base 22, the slide clamp fits in a sliding fashion through thetwo rail channels 72 in the base. Alignment of the slide clamp with thebase is accomplished by the fit of the slide clamp into the railchannels. Turning now to FIG. 7, the rails 70 and channels 72 can beseen more clearly. Additionally, it will be noted that the entireproximal end 74 of the base is enclosed. The center section 76 has beenleft open to accommodate the pulling projections of the slide clamp, aspreviously shown. Also more clearly seen is the distal free end 62 ofthe locking arm, as well as the releasing tab 64.

FIG. 8 shows a stop 78 formed on the top surface 28 of the base 22 thatlimits the range of movement of the release tab 64. In particular, astop surface 80 is spaced away from the back of the releasing tab by apreselected distance so that the tab cannot be overstressed by bendingit too far. Referring also to FIG. 9, a cross-section of the locking arm60 with releasing tab 64 formed at its end is shown. It will be notedthat the locking arm is molded as part of the base and is in acantilever form. The releasing tab 64 is disposed at approximatelyninety degrees to the locking arm but because the locking arm is formedat an angle to the upper 28 and the lower 82 surfaces of the base 22 soas to engage the slide clamp, the ninety degree angle of the releasingtab with the locking arm is other than ninety degrees to the top surfaceof the base. FIG. 9 more clearly illustrates the downward slope of thelocking arm 60 to create the necessary downward bias to engage thedetent 48 and locking edge 50 of the slide clamp to prevent the slideclamp from being moved to its open position until the locking arm 60 ismoved out of the detent by intended action of the operator.

Referring now to FIG. 10, a right side view of the base is provided. Itwill be seen that the angle of the top surface of the locking arm isapproximately 172.86 degrees relative to the top surface 28 of the base.This is also seen in FIG. 9. It has been found that thickening thelocking arm and providing the angles shown results in repeatableperformance. That is, when a releasing boss 90 (shown in FIG. 13)presses against the releasing tab 64, the tab and locking arm will riseaway from the base and therefore away from the mounted slide clamp thusreleasing the slide clamp for movement to the open position. This isdiscussed below in more detail. FIG. 11 presents a bottom view of thebase 22 showing more clearly the distal end 62 of the locking arm thatis received by the detent 48 of the slide clamp 24. Further, FIG. 11shows the aperture 49 through the base for the tube.

FIG. 12 shows the assembled slide clamp 24 and base 22 into anoperational automatic clamp apparatus 20 in accordance with aspects ofthe invention. Further, the clamp apparatus 20 is in the open positionduring which fluid may flow through the clamp apparatus. It will be seenthat the distal free end 62 of the locking arm 60 resides in the ramparea 52, but the ramp is formed to be deep enough so that the distalfree end 62 of the locking arm is not touching the material of the baseand therefore, the locking arm is in an unstressed condition. In thisconfiguration, the clamp apparatus 20 is in its smallest form therebyfitting into a pump with a closed door.

FIGS. 13 and 14 show in general how the automatic clamp apparatus 20 inaccordance with aspects of the invention interacts with the door of apump housing. FIG. 13 shows the slide clamp 24 in its occluding positionrelative to the base 22, with the slide clamp partially withdrawn fromthe base and the distal free end 62 of the locking arm 60 engaging thelocking detent 48 (not shown) to hold the slide clamp in its occludingposition. FIG. 14 shows the slide clamp in its open position with theslide clamp fully inserted within the base and the distal free end 62 ofthe locking arm flexed upwardly a sufficient amount to clear the detent48.

Operative elements of the door and latch mechanism are shownschematically and designated as elements 90, 92, and 94, to illustratetheir interaction with the automatic clamp apparatus of the presentinvention. A releasing boss 90 can be formed on the door and positionedto contact the release tab 64 as the door is moved to the closedposition, and to press the release tab up and back. A pushing boss 92can be formed on the latch mechanism and positioned to contact thepushing flange 44 on the slide clamp 24 as the latch is engaged to pushthe slide clamp from its occluding position (FIG. 13) to its openposition (FIG. 14). Finally, one or more pulling hooks 94 can be formedon the latch mechanism and positioned to contact the pulling projections54 as the latch is disengaged to pull the slide clamp 24 from its openposition to its occluding position.

The releasing boss 90 and the pushing boss 92 of the door move generallyto the right direction as seen in FIG. 13 when the door of the pump ismoved to the closed position. The pulling hook 94 of the latch mechanismcan be made to move generally to the left as seen in FIG. 14 when thelatch is being disengaged, and to the right when the latch is beingengaged, it being understood that other elements (not shown) of thelatch mechanism perform the actual latching of the door in the shutposition. In addition, the pulling hook 94 can rotate in the clockwisedirection from the position shown, relative to the remainder of thelatch mechanism, against a spring bias. For convenience, the conduitthrough the automatic clamp apparatus 20 is shown as a tube 96 in FIGS.13 and 14. In FIG. 13, the tube 96 is occluded by the slide clampaperture and is spread into the occluding slot of that aperture. In FIG.14, the tube is in the flow configuration. As mentioned above, a tubemay or may not be used as the conduit through the clamp apparatus 20. Atower may be used with parts of tube formed to the tower.

Referring briefly to FIG. 15, the inclusion of a pressure interfacedevice 100 upstream of the automatic clamp apparatus 20 is shown. Thispressure interface device may take the form of a pressure diaphragm 101having a size and configuration to be mounted to a pressure sensor thatis a part of the infusion pump to which the clamp apparatus is to bemounted. Such a pressure diaphragm device is shown in U.S. Pat. No.4,398,542 to Cunningham, and incorporated herein by reference. A sensorusable with such a pressure diaphragm is shown in U.S. Pat. No.4,404,440 to Busche, also incorporated herein by reference. Mountingsuch a pressure diaphragm in line with the automatic clamp apparatus ofthe invention would restrict movement of the clamp apparatus along theline since it will need to be adjacent the pressure diaphragm to befitted into the pump. In such a case, the tower 26 may be used as amount for the pressure diaphragm device.

Operation

To use the automatic clamp apparatus 20 of the present invention, theslide clamp 24 is assured to be in the occluded position, as shown inFIG. 1. Because the locking arm 60 is located in the detent 48, theslide clamp cannot be moved from the occluding position to the openposition unless the release tab 64 is actuated. While in the detent, thelocking arm is unstressed. The upstream end of the IV tube 96 isconnected to a fluid supply (not shown) of the chosen fluid to bepumped. The administration set containing the automatic clamp apparatusof the invention may be primed if necessary by the operator pressing adigit against the release tab to move it and the locking arm upwards outof the detent and another digit against the pushing flange to move theslide clamp to the open position. As the slide clamp is inserted intothe base, the locking arm moves down the ramp 52 to the bottom of theramp (FIG. 12) where it is unstressed. Priming may now occur. Onceprimed, the pushing flange is grasped by the operator and withdrawn fromthe base to restore the slide clamp to the occlusion position as shownin FIG. 1 so that the free flow of fluid through the IV tube cannotoccur.

The door of the pump housing is opened and the automatic clamp apparatus20 and tubing above and below the clamp apparatus 20 are installed intothe pump appropriately. The pushing flange is used by the operator toreceive a digit of the operator for pushing the clamp apparatus into theappropriate cavity of the pump. The clamp apparatus should remain in theocclusion configuration during this installation into the pump. Becausethe release tab is off center in relation to the pushing flange, thechances of the operator pressing it instead or with, the pushing flangeare greatly reduced.

The upstream and downstream tubing is now engaged with any other devicesthat exist, such as an air-in-line sensor, pressure sensors, etc.Especially, the pumping tube 96 is placed in contact with the pumpingmechanism, and the door of the pump is then shut. FIG. 13 shows theslide clamp 24 in its occluding position, with the release boss 90 aboutto contact the release tab 64 as the door of the pump is shut. As thedoor is completely shut, the release boss 90 presses the release tab 64upward thereby flexing the locking arm 60 upward and out of the detent48 thereby permitting movement of the slide clamp so that it can beinserted into the base. After the door is completely shut, the latchingmechanism is latched, causing the pushing boss 92 to push the slideclamp 24 and insert it into the base to its open position as shown inFIG. 12. FIG. 14 shows the slide clamp 24 in its open position, with thepulling hook 94 having pivoted behind the pulling projection 54. Thepump can then be operated in the conventional fashion to purge the IVtube 96 of air, and the IV tube 96 can be connected to a venous accesssite.

When the pump door is to be opened, the boss 92 and the hook 94 will bemoved to the left, causing the pulling hooks 94 to contact the pullingprojection 54 of the slide clamp 24 and withdraw the slide clamp 24 fromthe base to its occluding position. The latching mechanism can beconstructed by known means so that only after this occlusion occurs willthe door be unlatched. At this time, the door can be opened. The lockingarm 60 having engaged the locking detent 48 maintains the slide clamp 24in its occluding position, even if the slide clamp 24 is pushed towardthe base 22 with considerable force.

The latching mechanism can also be constructed by known means so thatwhen the door has been unlatched, the latching mechanism can not bemoved back to its latched position until the door has been shut.Therefore, if the door is to be shut, the releasing boss 90 will pressthe release tab 64 upward to release the locking arm 60 from engagementwith the detent 48, and the slide clamp 24 can be subsequently moved tothe open position as explained before.

While the particular automatic clamp apparatus as herein shown anddisclosed in detail is fully capable of obtaining the objects andproviding the advantages herein before stated, it is to be understoodthat it is merely illustrative of the presently preferred embodiments ofthe invention and that no limitations are intended to the details ofconstruction or design herein shown other than as described in theappended claims.

1. A clamp apparatus for selectively preventing fluid flow through aresilient tube, comprising: a base having a tube aperture at which theresilient tube may be located, the base having a longitudinal centerline; a slide clamp slidably mountable on the base for movement betweenan occluding position and an open position, the slide clamp having alongitudinal center line; a clamp aperture formed in the slide clamp forreceiving the tube therethrough; a constricted region formed in theclamp aperture, the constricted region occluding the tube to preventfluid flow through the tube when the slide clamp is in the occludingposition; an open region formed in the clamp aperture, the open regionallowing fluid flow through the tube when the slide clamp is in the openposition; a flexible cantilevered locking arm mounted on the base, thelocking arm being biased toward a locking position to prevent movementof the slide clamp from the occluding position to the open position, thelocking arm being deflectable to allow subsequent movement of the slideclamp from the occluding position to the open position; and a detent inthe slide clamp into which the locking arm is biased to the lockingposition and into which the locking arm is located when the slide clampis in the occluding position to prevent the slide clamp from moving fromthe occluding position, the detent being large enough to receive thelocking arm such that the locking arm is unstressed while in the detent;wherein the locking arm further comprises a release tab for releasingthe flexible arm from the slide clamp, to allow subsequent movement ofthe slide clamp from the occluding position to the open position; andwherein the release tab is located at a position offset from thelongitudinal center line of the base.
 2. The clamp apparatus of claim 1wherein the tube aperture of the base slidably receives the resilienttube such that the base may be slid along the tube to a selectedposition when the slide clamp is in the open position.
 3. The clampapparatus of claim 1 wherein the base further comprises a stop surfacelocated at a position adjacent the release tab to interfere withmovement of the release tab beyond a preselected range of movement. 4.The clamp apparatus of claim 1 wherein the release tab is disposed fordeflecting the flexible arm out of the detent to allow subsequentmovement of the slide clamp from the occluding position to the openposition.
 5. The clamp apparatus of claim 1 wherein the slide clampfurther comprises a ramp to receive the locking arm when the slide clampis in the open position, the ramp formed to be deeper than the armwhereby the arm is unstressed when the slide clamp is in the flowposition.
 6. The clamp apparatus of claim 5 wherein the ramp is formedto guide the locking arm into the detent formed in the slide clamp asthe slide clamp is being moved from the open position to the occludingposition to thereby lock the slide clamp in the occluding position. 7.The clamp apparatus of claim 1 wherein: the aperture is approximatelytear-drop shaped; the constricted region comprises an elongated slotportion; the flow region comprises a rounded portion; the tube islocated in the slot portion when the slide clamp is in the occludingposition; and the tube is located in the round portion when the slideclamp is in the open position.
 8. The clamp apparatus of claim 1 whereinthe tube aperture comprises a tower into which a tube end may beattached.
 9. The clamp apparatus of claim 1 wherein the tube aperturecomprises a fluid passageway through the base, whereby the resilienttube is connected in fluid communication with the passageway.
 10. Theclamp apparatus of claim 1 further comprising a pressure interfacedevice located between the resilient tube and the base, the pressureinterface device having a pressure diaphragm mounted in a housing, thepressure diaphragm formed to conduct pressure increases and decreases ofthe resilient tubing to a pressure sensor.
 11. A clamp apparatus forselectively preventing fluid flow through a resilient tube, comprising:a base having a tube aperture at which the resilient tube may belocated, the base having a longitudinal center line; a slide clampslidably mountable on the base for movement between an occludingposition and an open position, the slide clamp having a longitudinalcenter line; a clamp aperture formed in the slide clamp for receivingthe tube therethrough; a constricted region formed in the clampaperture, the constricted region occluding the tube to prevent fluidflow through the tube when the slide clamp is in the occluding position;an open region formed in the clamp aperture, the open region allowingfluid flow through the tube when the slide clamp is in the openposition; a flexible cantilevered locking arm mounted on the base, thelocking arm being biased toward a locking position to prevent movementof the slide clamp from the occluding position to the open position, thelocking arm being deflectable to allow subsequent movement of the slideclamp from the occluding position to the open position; and a detent inthe slide clamp into which the locking arm is biased to the lockingposition and into which the locking arm is located when the slide clampis in the occluding position to prevent the slide clamp from moving fromthe occluding position, the detent being large enough to receive thelocking arm such that the locking arm is unstressed while in the detent;wherein the slide clamp further comprises a front pushing flange largeenough to receive a digit of an operator used to push the clampapparatus into position in a medical infusion pump, the pushing surfacebeing concave.
 12. The clamp apparatus of claim 11 wherein the releasetab is located at a position other than behind the pushing flange. 13.The clamp apparatus of claim 12 the release tab is located at a sidewaysposition in relation to the pushing flange.
 14. A clamp apparatus forselectively preventing fluid flow through a resilient tube, comprising:a base having a tube aperture at which the resilient tube may belocated, the base having a longitudinal center line; a slide clampslidably mountable on the base for movement between an occludingposition and an open position the slide clamp having a longitudinalcenter line; a clamp aperture formed in the slide clamp for receivingthe tube therethrough; a constricted region formed in the clampaperture, the constricted region occluding the tube to prevent fluidflow through the tube when the slide clamp is in the occluding position;an open region formed in the clamp aperture, the open region allowingfluid flow through the tube when the slide clamp is in the openposition; a flexible cantilevered locking arm mounted on the base, thelocking arm being biased toward a locking position to prevent movementof the slide clamp from the occluding position to the open position, thelocking arm being deflectable to allow subsequent movement of the slideclamp from the occluding position to the open position; and a detent inthe slide clamp into which the locking arm is biased to the lockingposition and into which the locking arm is located when the slide clampis in the occluding position to prevent the slide clamp from moving fromthe occluding position the detent being large enough to receive thelocking arm such that the locking arm is unstressed while in the detent;wherein: the locking arm further comprises a release tab for releasingthe flexible arm from the slide clamp, to allow subsequent movement ofthe slide clamp from the occluding position to the open position; thebase further comprises a stop surface located at a position adjacent therelease tab to interfere with movement of the release tab beyond apreselected range of movement; the slide clamp comprises a ramp toreceive the locking arm when the slide clamp is in the open position,the ramp formed to be deeper than the locking arm whereby the lockingarm is not under stress when the slide clamp is in the flow position,the ramp further formed to guide the locking arm into the detent as theslide clamp is being moved from the open position to the occludingposition to thereby lock the slide clamp in the occluding position; theslide clamp further comprises a front pushing flange large enough toreceive a digit of an operator used to push the clamp apparatus intoposition in a medical device, the pushing surface being concave; and therelease tab is located at a position other than behind the pushingflange.
 15. The clamp apparatus of claim 14 wherein the release tab islocated at a sideways position in relation to the pushing flange.